Integral fin apparatus

ABSTRACT

Apparatus for forming an integrally finned tube having at least one intermediate land, the land being obtained by skip-finning. A mechanism operable to initiate the skip-finning cycle has at least a portion thereof positioned to contact the advancing tube. The tube contacting portion of the mechanism is held out of contact with the tube when the skip-finning cycle has been completed and the finning operation has restarted.

I United States Patent 1 3,589,158

[72] Inventors Albert J. Kallfelz {56] References Cited Camillus; UNITED STATES PATENTS Syracuse 2,760,898 8/1956 Hill 72/104 16.2 1969 3,296,451 1/1967 Prutton 72/100 Patented June 197 3,379,042 4/1968 Brown, Jr. 72/96 [73} Assignee Carrier Corporation Primary ExaminerGranville Y. Custer, Jr.

Syracuse, N Y Attorneys-Harry G. Martin, Jr. and J. Raymond Curtin ABSTRACT: Apparatus for forming an integrally finned tube (54] g P QF having at least one intermediate land, the land being obtained rawmg by skip-finning. A mechanism operable to initiate the skip- [52] U.S. Cl 72/98, firming cycle has at least a portion thereof positioned to con- 72/ 100, 72/ 104 tact the advancing tube. The tube contacting portion of the [5 1] Int. Cl B2lh 3/12 mechanism is held out of contact with the tube when the skip- [50] Field 0t Search 72/96, 98, finning cycle has been completed and the finning operation has restarted.

PATENTEU JUN29 1971 INVENTORS. ALBERT J. KALLFELZ.

BY FRANK F. WALTERS.

ATTORNEY.

INTEGRAL FIN APPARATUS BACKGROUND OF THE INVENTION This invention relates to the manufacture of integrally finned tubing of the kind used in heat transfer apparatus, and more particularly, it relates to the manufacture of finned tubing having integral bearing portions intermediate their ends, whereby the tubes may be expeditiously assembled with and adequately supported in a heat transfer apparatus.

Integral helical external fins are formed on lengths of tubing by subjecting the tubing to a circumferential rolling pressure radially inward against axially spaced peripheral portions of a tube, to extrude material from the wall of the tubing radially outward to form fins. The apparatus for forming integral fins on tubing generally includes a plurality of forming roll assemblies which are precision spaced about the tube and are mounted to move towards the tube. Each forming roll assembly has die means mounted on a supporting arbor. The die means define axially spaced peripheral portions with grooves formed therebetween. The die means are commonly discs which are graduated in diameter and width to progressively form fins of the desired size and height.

Preferably, three forming roll assemblies are mounted with their axes essentially parallel to each other but spaced l apart. The axes of the roll assemblies are at a slight skew angle in the customary manner, so as the tube is advanced through the apparatus, the fins will be formed about the surface to define a helical configuration. Radial movement of the roll assemblies is controlled by sleeve-shaped cams, each of the arbors being mounted in an associated cam. The sleeve-shaped cams are joumaled within mating bores disposed on the inner surface of a substantially cylindrical member, the outer surface thereof defining the outer periphery of the tube finning head assembly, the member forming a housing for the other components of the assembly. The matin g bores establish the desirable skew angle for the axes of the roll assemblies.

In heat transfer apparatus requiring the use of relatively long finned tubing, it is customary to provide one or more apertured plates intermediate the ends of the apparatus for supporting intermediate portions of the tubing. The openings or apertures in the plates generally have a diameter at least equal to the outside diameter of the fins on the tubing in order to enable the tubing to be freely extended through these openings during assembly or replacement of the tubing. This requirement complicates the problem of adequately supporting the finned tubing intermediate their ends, because the outer edges of the fins do not afford sufficient bearing area and because the fins are not sufficiently rigid to adequately withstand the stresses applied to the tubing during shipment and operation of the heat transfer apparatus.

To accommodate the support plates, the general practice has been to leave certain predetermined portions of the tubing unfinned. The unfinned portions, hereinafter referred to as lands," serve as the requisite bearing portions. The method commonly used to obtain the lands is known as skip finning to those skilled in the art.

Basically, the skip-finning cycle comprises withdrawing the forming roll assemblies from their contact with the tubing at predetermined intervals. A clamp-type mechanism mounted on the finning machine will then engage the tubing and move the tubing axially forward in its path of travel a predetermined distance, thus leaving that portion of the tubing unfinned as desired.

Heretofore, the mechanisms used for initiating the skipfinning cycle have been unreliable. These mechanisms ineluded electric eyes and air probes. A plurality of these devices would generally be mounted on the finning machine. The forward end of the tube, crossing the electrical beam of the eye or the air circuit of the probe, would short circuit the particular means used, thereby initiating the skip-finning cycle.

The electric eyes or air probes easily became fouled by chips of stock, dirt and coolant used on the tubing during the finning operation. The fouling of the eyes and probes greatly increased maintenance costs, since they had to be cleaned very often and new ones had to be installed quite frequently. In addition, initiation ofthe skip-finning cycle was not uniform due to the inherent time delay due to the reaction time of the particular mechanism involved.

To try to overcome the problems of fouling due to dirt, the electric eyes were placed relatively remote from the tubing. A metallic arm associated with each electric eye, extended into the path of travel of the tubing. The forward end of the tubing would strike the arm, which in turn would short circuit the electric eye beam.

Not only did this indirect method of initiating the skip finning cycle further increase the undesirable staggering of the lands, but the metallic arm remained in the path of travel of the tubing and hammered the fins as they passed by. The hammer action caused dents in the fins which, in severe cases, resulted in the tubing being unfit for use in the heat transfer apparatus. Additionally, the arms quickly wore out, thus increasing maintenance costs even further.

The object of this invention is a mechanism for initiating the skip-finning cycle having none of the defects heretofore discussed and additionally, one that is less expensive initially to install on an integral finning machine.

SUMMARY OF THE INVENTION The present invention relates to a tube finning machine including a mechanism operable to initiate a skip-finning cycle. The mechanism includes a movable arm positioned in the path of travel of an advancing tube to be contacted thereby. Result ing movement of the arm initiates the skip-finning cycle. The arm is thereafter held out of contact with the advancing tube.

The invention also relates to a method of providing a land on finned tubing in which the skip-finning initiating mechanism is held out of contact with the advancing tube once the land has been obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a length of tubing, having integral fins formed thereon, with intermediate bearing portions or lands";

FIG. 2 perspectively shows a portion of an integral finning machine and the controls therefor, including the novel mechanism; and

FIG. 3 is a schematic illustration of the wiring diagram for the control circuit utilized with the novel mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown a preferred embodiment of the invention and the manner in which the in vention is employed to obtain the desired intermediate bearing portion, or land, on a length of tubing having integral, helical fins formed thereon. In referring to the drawings, like numerals shall refer to like parts.

In particular, FIG. 1 shows a length of tubing 10 having an external, integral helical fin 11 formed thereon. A plurality of lands 12 are formed at predetermined intervals on the length of tubing 10.

Referring now to FIGS. 2 and 3, there is shown a portion of apparatus used to manufacture integral fins and a control circuit operable to obtain at least one land on a length of tubing.

The apparatus of FIG. 2 includes a finning head assembly 59. A detailed description of the finning head assembly may be found in copending application Ser. No. 803,895, filed Mar. 3, 1969, entitled Apparatus for Producing External Integral Fins for Tubing, Frank F. Walters, inventor. The assembly 59 includes an outer housing 60. Mounted within the housing 60 is a cam member 61 which controls the radial movement of fin forming roll assemblies 63. Roll assemblies 63 comprise an arbor 64 with discs 62 mounted thereon. The

integral fin is formed on the tubing by moving assemblies 63 radially inward until discs 62 engage the tubing. In a preferred embodiment, three forming roll assemblies 63 are utilized, the assemblies being spaced circumferentially about the path of travel of the tubing, which is indicated by reference numeral a. Control arm 65, connected to cam member 61, controls the radial movement of the forming roll assemblies 63 into and out of engagement with the tubing. As shown, the discs are in their clearance position. The manner in which arm 65 is controlled shall be explained more fully hereinafter.

Associated with the finning head 60 is tube positioning means including a carriage 17 mounted on rail members 18 and 18a. The carriage is connected to means for effecting movement thereof axially of the path of travel 10a of the tubing, and this means is illustrated as comprising a fluid actuated piston and cylinder device 15, the piston rod of which is indicated as 71 is connected to the carriage 17. Movement of the carriage is controlled by admitting fluid to one end or the other of the cylinder of the piston and cylinder device and this in turn is controlled by a solenoid actuated valve 32. The manner in which valve 32 is controlled shall be explained more fully hereinafter. In addition to the carriage, the tube positioning means includes clamp mechanism 16 which is mounted on the carriage. The clamp mechanism 16 includes clamping jaws 16a and 16b, adapted to be moved toward and away from each other in clamping and releasing strokes by a tube clamping piston and cylinder device 14. Device 14 is similar in design to device 15 and is controlled by solenoid actuated valve 28. As will be explained hereinafter, the jaws of clamp mechanism 16 are designed to engage the circumference of the tubing when it is desired to provide a land. With the clamp device 16 in engaging relationship with the tubing, the carriage 17, the clamp device 16 and the tubing move axially forward in the direction of the path of travel of the tubing, a distance equal to the desired width of the land.

As noted hereinbefore, lands are generally formed on integral finned tubing by what is known in the relevant art as skip finning. The invention relates to a novel mechanism, operable to initiate the skip-flnning cycle.

The skip-finning initiating mechanism 19 includes an arm 48 positioned to extend into the path of travel of the tube. The advancing tube will contact the arm 48 and cause the arm to rotate. Connected to the arm and rotatable therewith is cam member 50. A portion of the periphery of cam member 50 defines a sinusoidal raceway 50a for cam follower 51. Cam follower 51 is connected to normally open limit switch 20. When arm 48 is rotated by the advancing tube, cam follower 51 moves along raceway 50a until it contacts the high point 50b of the raceway. With cam follower 51 in contact with point 50b, limit switch 20 is closed. Closure of switch 20 starts the skip-finning cycle as will be explained more fully hereinafter.

The advancing tube causes arm 48 to continue to rotate until cam follower 51 is out of contact with point 50b of raceway 5011. A biasing member such as a spring (not shown) returns switch 20 to its normally open position. ln addition, the biasing member maintains cam follower 51 in contact with raceway 50a, and causes cam 50 to rotate until cam follower 51 reaches low point 50c of raceway 50a. With cam follower 51 in contact with point 500, arm 48 no longer extends into the path of travel of the tube. Cam follower 51 remains in engagement with point 50c during the remainder of the finning cycle, thereby maintaining arm 48 out of contact with the finned tubing, thus eliminating the prior art problems heretofore noted.

Referring now particularly to FIG. 3, a preferred control circuit for the apparatus heretofore discussed is shown. A source of current (not shown) is represented by L and L Assume a tube is being finned; thus discs 62 are engaging the tube. When the advancing tube contacts arm 48 of mechanism 19 controlling normally open switch 20, cam 50 is caused to rotate so cam follower 51 contacts point 50b and switch 20 closes. The closing of switch 20 energizes control relay 23,

thereby closing normally open switch 24 and creating a hold ing circuit around switch 20. Thus, when switch 20 opens due to the continued rotation of cam 50, control relay 23 remains energized. Relay 23 controls the operation of normally open switches 26 and '27. Switch 26 closes immediately upon the energization of relay 23. Closing switch 26 energizes one coil 25a of solenoid valve 25. When coil 25a isenergized, motivating fluid, such as compressed air, is delivered via line 40, from a source of supply (not shown), to line 71. Line 71 communicates with piston and cylinder device 13, this device being similar in construction to devices 14 and 15 previously explained. Piston rod of device 13 is connected to control arm 65 and operates to move the arm from the dotted line position to the solid line position, as shown in FIG. 2, when coil 25a is energized. Arm 65 thereby rotates cam 61 so arbors 64 are moved radially outward and discs 62 mounted thereon, are disengaged from the tubing being finned.

Switch 27 does not close immediately. The delayed closing is shorter than the time required to move discs 62 to their fully disengaged position. When switch 27 closes, a circuit is completed through normally closed switch 29, to energize valve 28. When energized, valve 28 operates to communicate compressed air supply line 52 with line 74. Line 74 delivers the compressed air to piston and cylinder device 14 so the jaws of clamp mechanism 16 engage the tube. It is desirable for the jaws 16a and 16b to engage the tube before the discs 62 are completely disengaged therefrom, to prevent the tube from wandcring" due to its high rotational speed.

When jaws 16a and 16b are tight on the tube, pressureopcrated switch 30 is closed. When discs 62 are completely disengaged from the tube, normally open switch 31 is closed. The closing of switches 30 and 31 complete a circuit energizing valve 32. With valve 32 energized, compressed air is delivered from supply line 42 to line communicating with piston and cylinder device 15. Piston rod 71 thereby operates to move carriage 17 axially forward in the direction of the path of travel 10a of the tube. Thus, the clamp mechanism 16 mounted on the carriage and the tube are likewise moved axially forward. The distance the tube is advanced determines the width of the land.

The closing of clamp mechanism 16 has opened normally closed switch 33. The forward advance of carriage 17 has closed normally open switch 34 and has opened normally closed switch 29. When switch 29 opens, solenoid valve 28 is deenergized. Supply line 52 is thereby placed in communication with line 73 and piston and cylinder device 14 operates to release jaws 16a and 16b from the tube. Wheh clamp mechanism 16 opens, switch 33 closes, completing a circuit to energize control relay 54. Energization of relay 54 opens normally closed switch 55 and closes normally open switch 56.

The opening of switch 55 deenergizes relay 23, thereby opening switches 26 and 27. When switch 27 opens, solenoid valve 32 is deenergized. Compressed air supply line 42 is then communicated with line 76, which delivers the compressed air to device 15 so piston rod 71 operates to return the carriage 17 to its starting position. 1

The closing of switch 56 and the opening of switch 26 operates to deenergize coil 25a and energize coil 25b of solenoid valve 25. With coil 25b energized, compressed air is transmitted from supply line 40 to line 72 communicating with device 13. Piston 70 thereby operates to move arm 65 to its dotted line position. Cam 61 is rotated so arbors 64 move radially inward until the discs 62 reengage the tube and the finning operation is restarted.

As noted above, a plurality of mechanisms 19 are generally employed, the number being equal to the number of lands desired on a length of tubing. FIG. 2 shows three mechanisms being used, each one controlling the operation of a switch, as shown, switches 21 and 22, similar to switch 20 previously described.

When a new tube is inserted into the flnning machine, switch 57 is closed, thereby energizing solenoid valve 58. With valve 58 energized, compressed air is transmitted from supply line 44 to supply branch 46 communicating with a plurality of piston and cylinder devices 47. The compressed air acts to drive piston rod 77 of device 47. The piston rod 77 contacts arms 49 of mechanisms 19. Arms 49 are rotatably connected to cams 50. The piston rods 77 cause the arms 49 to rotate, thereby rotating cams 50 and arms 48 connected thereto. The rotation of the arms 48 is effected so that they are returned to their operating position, extending into the path of travel of the tube.

The novel land-start mechanism herein disclosed is more durable, more reliable and less expensive when compared to the land-start mechanisms heretofore employed.

While we have described and illustrated a preferred embodiment of our invention, our invention is not limited thereto, but may be embodied within the scope of the following claims.

We claim:

1. The method of forming finned tubing having at least one intermediate land comprising the steps of:

A. rotating a length of tubing between a plurality of inclined finning rolls to form fins on the tubing, while advancing the tubing to bring adjacent unfinned portions of tubing progressively into engagement with the rolls to form a continuous helical fin;

B. placing an actuating member in the path of the advancing and rotating tubing;

C. advancing the tubing to contact said member to actuate mechanism to discontinue finning;

D. advancing the tubing longitudinally a distance equal to the desired width of the land while the finning operation is discontinued;

E. resuming the finning operation while rotating and advancing the tubing; and

F. holding said member from contact with the advancing and rotating tubing when the finning operation is resumed.

2. Apparatus for forming finned tubing having at least one intermediate land comprising:

A. means for rotating and advancing the tubing while providing the tubing with fins;

B. means operable to provide a land on said tubing, said means including a movable arm placed in the path of travel of the advancing tubing to be contacted thereby to discontinue operation of the first means;

C. means for advancing the tubing a distance equal to the desired width of the land when the finning operation is discontinued;

D. means for resuming the finning operation; and

E. means for holding said movable arm from contact with the rotating and advancing tubing when the finning operation is resumed.

3. Apparatus in accordance with claim 2 wherein said means operable to provide a land includes:

A. cam means rotatably connected to said movable arm;

and

B. cam follower means engaging said cam means and moveable therewith, said cam follower means being operable to hold said movable arm from contact with said tubing when said land has been obtained.

4. Apparatus in accordance with claim 3 wherein at least a portion of the periphery of said cam means defines a sinusoidal raceway for said cam follower means.

5. Apparatus in accordance with claim 4 wherein said fin providing rotating and advancing means includes:

a plurality of forming roll assemblies positioned with their axes spaced laterally from and substantially equally spaced around the axis along which said tubing advances during a progressive finning operation.

6. Apparatus in accordance with claim 5 wherein said forming roll assemblies comprise:

A. a plurality of arbors; and

B. a plurality of discs mounted on each of said arbors for rotation therewith, said discs being of generally increasmg diameter in the direction of a vance of said tubing,

said discs engaging said tubing during the finning operation.

7. Apparatus in accordance with claim 6 wherein said means operable to advance said tubing the distance equal to the desired width of the land comprises:

a plurality of rail members;

B. a carriage slidably mounted on said rail members, said movement being axial relative to the path of travel of said tubing;

C. clamp means mounted on said carriage to move therewith, said clamp means including a pair of opposed jaws adapted to be moved toward and away from each in clamping and releasing strokes, said jaws engaging said tubing when said finning operation has been interrupted to provide the land.

8. Apparatus in accordance with claim 2 wherein said fin providing rotating and advancing means includes:

a plurality of forming roll assemblies positioned with their axes spaced laterally from and substantially equally spaced around the axis along which said tubing advances during a progressive finning operation.

9. Apparatus in accordance with claim 8 wherein said forming roll assemblies comprise:

A. a plurality of arbors; and

B. a plurality of discs mounted on each of said arbors for rotation therewith, said discs being of generally increasing diameter in the direction of advance of said tubing, said discs engaging said tubing during the finning operation.

10. Apparatus in accordance with claim 2 wherein said means operable to advance said tubing the distance equal to the desired width of the land comprises:

A. a plurality of rail members;

B. a carriage slidably mounted on said rail members, said movement being axial relative to the path of travel of said tubing; and

C. clamp means mounted on said carriage to move therewith, said clamp means including a pair of opposed jaws adapted to be moved toward and away from each in clamping and releasing strokes, said jaws engaging said tubing when said finning operation has been interrupted to provide the land. 

1. The method of forming finned tubing having at least one intermediate land comprising the steps of: A. rotating a length of tubing between a plurality of inclined finning rolls to form fins on the tubing, while advancing the tubing to bring adjacent unfinned portions of tubing progressively into engagement with the rolls to form a continuous helical fin; B. placing an actuating member in the path of the advancing and rotating tubing; C. advancing the tubing to contact said member to actuate mechanism to discontinue finning; D. advancing the tubing longitudinally a distance equal to the desired width of the land while the finning operation is discontinued; E. resuming the finning operation while rotating and advancing the tubing; and F. holding said member from contact with the advancing and rotating tubing when the finning operation is resumed.
 2. Apparatus for forming finned tubing having at least one intermediate land comprising: A. means for rotating and advancing the tubing while providing the tubing with fins; B. means operable to provide a land on said tubing, said means including a movable arm placed in the path of travel of the advancing tubing to be contacted thereby to discontinue operation of the first means; C. means for advancing the tubing a distance equal to the desired width of the land when the finning operation is discontinued; D. means for resuming the finning operation; and E. means for holding said movable arm from cOntact with the rotating and advancing tubing when the finning operation is resumed.
 3. Apparatus in accordance with claim 2 wherein said means operable to provide a land includes: A. cam means rotatably connected to said movable arm; and B. cam follower means engaging said cam means and moveable therewith, said cam follower means being operable to hold said movable arm from contact with said tubing when said land has been obtained.
 4. Apparatus in accordance with claim 3 wherein at least a portion of the periphery of said cam means defines a sinusoidal raceway for said cam follower means.
 5. Apparatus in accordance with claim 4 wherein said fin providing rotating and advancing means includes: a plurality of forming roll assemblies positioned with their axes spaced laterally from and substantially equally spaced around the axis along which said tubing advances during a progressive finning operation.
 6. Apparatus in accordance with claim 5 wherein said forming roll assemblies comprise: A. a plurality of arbors; and B. a plurality of discs mounted on each of said arbors for rotation therewith, said discs being of generally increasing diameter in the direction of advance of said tubing, said discs engaging said tubing during the finning operation.
 7. Apparatus in accordance with claim 6 wherein said means operable to advance said tubing the distance equal to the desired width of the land comprises: a plurality of rail members; B. a carriage slidably mounted on said rail members, said movement being axial relative to the path of travel of said tubing; C. clamp means mounted on said carriage to move therewith, said clamp means including a pair of opposed jaws adapted to be moved toward and away from each in clamping and releasing strokes, said jaws engaging said tubing when said finning operation has been interrupted to provide the land.
 8. Apparatus in accordance with claim 2 wherein said fin providing rotating and advancing means includes: a plurality of forming roll assemblies positioned with their axes spaced laterally from and substantially equally spaced around the axis along which said tubing advances during a progressive finning operation.
 9. Apparatus in accordance with claim 8 wherein said forming roll assemblies comprise: A. a plurality of arbors; and B. a plurality of discs mounted on each of said arbors for rotation therewith, said discs being of generally increasing diameter in the direction of advance of said tubing, said discs engaging said tubing during the finning operation.
 10. Apparatus in accordance with claim 2 wherein said means operable to advance said tubing the distance equal to the desired width of the land comprises: A. a plurality of rail members; B. a carriage slidably mounted on said rail members, said movement being axial relative to the path of travel of said tubing; and C. clamp means mounted on said carriage to move therewith, said clamp means including a pair of opposed jaws adapted to be moved toward and away from each in clamping and releasing strokes, said jaws engaging said tubing when said finning operation has been interrupted to provide the land. 